Operation Litani

Operation Litani occurred from 14 to 21 March 1978 when Israel invaded South Lebanon with the goal of evicting the Palestine Liberation Organization from its bases on the Lebanese border with northern Israel. The operation succeeded in displacing the PLO, which fled to Beirut, but it also caused the displacement of up to 250,000 Lebanese civilians.

Background
In 1968, the Palestinian nationalist Palestine Liberation Organization set up several guerrilla camps in South Lebanon, from which they raided civilian targets in Israel and carried out worldwide terror attacks against Jewish targets. In the aftermath of Black September in Jordan in 1971, 3,000 PLO militants fled from Jordan to Lebanon, and Israel periodically launched raids into Lebanon to retaliate for terrorist attacks. By October 1977, 300,000 Shi'ite Muslim refugees fled South Lebanon, and the conflict between the PLO and Israel led to clashes between the Maronite and Druze minorities of Lebanon and the Muslim majority and the start of the Lebanese Civil War. On 11 March 1978, the PLO committed an egregious atrocity in the Coastal Road massacre, killing 38 Israeli civilians (including 13 civilians) and wounding 76 after hijacking two buses in northern Israel. This, combined with the PLO's relentless shelling of northern Israel, led to the Israelis retaliating with a full-scale invasion of South Lebanon.

War
After an air, artillery, and naval bombardment of South Lebanon, 25,000 Israeli IDF troops invaded South Lebanon, with Israeli paratroopers capturing all of the bridges on the Litani River and cutting off a PLO retreat. Most of the PLO fighters avoided battle and fled, and many Lebanese civilians were killed in Israeli artillery bombardments and airstrikes; the United States was angered that Israel had used US-provided cluster bombs for the bombing of Lebanon, as President Jimmy Carter had arranged that the cluster bombs could only be used if Israel was being attacked by its Arab rivals. A total of 550 PLO fighters and 1,500 civilians were killed, while 250,000 civilians were internally displaced. After the US threatened to cut off aid to Israel, Prime Minister Menachem Begin was forced to end the operation a week after its start, on 21 March 1978. The United Nations sent peacekeeping forces to South Lebanon to restore security in the region, and Israel left their occupied territories under the Christian South Lebanon Army's control. Both the SLA and the PLO attacked the UN peacekeeping forces, and intensified fighting in the south led to the First Lebanon War of 1982.